法庭科学的表述与法律证明

法庭科学评价意见在法庭上陈述的方式应当与法官所要求、陪审团实际应用的刑事证明程序相兼容。这并非一个数值性的归纳过程，而是在探求排除合理怀疑证明标准下的“最佳解释推理”。面临的问题并不是控方主张的数学概率问题，而是在全面考量了法庭上出示的所有证据后，控方主张是否为唯一可解释假说的问题。为确保陪审团仍然能专注地运用这一法律证明标准，笔者主张，控方提出的评价性法庭科学证据不应当以似然比的形式在强调若控方主张为真便更有可能认定证据，而应聚焦于本方证据对辩方有利的解释范围并在被告被定罪之前排除掉所有这些解释的合理可能性。

Forensic science expressions and legal proof

Evaluative forensic science opinions should be presented in a form that can be accommodated within that process of criminal proof demanded by judges and applied by juries. This is a non-mathematical inductive process that seeks ＇the inference to best explanation＇ to a standard of proof beyond reasonable doubt. The question posed is not the mathematical probability of the prosecution hypothesis but whether, having regard to all the evidence properly before the court, the prosecution hypothesis is the only explicable hypothesis. To ensure that a jury remains focused on applying this legal standard it is argued that evaluative forensic science evidence tendered by the prosecution should be expressed not as a likelihood ratio that emphasizes the greater likelihood of finding evidence if the prosecution＇s contentions are true, but in a form that emphasises the ranges of explanations for the evidence consistent with the defence case and that must be excluded as a reasonable possibility having regard to all the evidence before the accused can be convicted.